Dielectric response of K(Ta,Nb)O3 thin films

The dielectric response of K(Nb,Ta)O₃ films grown on (001) MgAl₂O₄ (100) by pulsed laser deposition from a mosaic target of KTa_0.63Nb_0.37O₃ and KNO₃ has been examined. In particular, the effects of growth temperature (650–800 °C), growth pressure (1–100 mTorr O₂), and annealing conditions on the tunability, dielectric constant, and dielectric losses in interdigitated capacitor device structures fabricated with these films are described. Annealing treatments lead to a reduction in the loss tangents for most of the films considered. Figure of merit calculations indicate that the best dielectric response (tunability=37%, tan =0.022) is achieved for films grown at 750 °C in an oxygen pressure of 100 mTorr and then annealing at 1000 °C for 2 h in air.